Cockpit Pressurization and Oxygen Warning System

ABSTRACT

A cockpit pressurization and oxygen warning system includes a cabin pressure input and an aircraft pressure input. A pilot interface includes a first visual indicator having a first recognizable characteristic disposed in a first position that is made visually perceptible when a first signal is asserted and a second visual indicator having a second recognizable characteristic esthetically different from the first recognizable characteristic and disposed in a second position different from the first position that is made visually perceptible when a second signal is asserted. A control circuit that is responsive to the cabin pressure input and the aircraft pressure input determines an acceptable range for the cabin altitude that corresponds to the aircraft altitude. The control circuit asserts the first signal when the cabin altitude is within the acceptable range and asserts the second signal when the cabin altitude is not within the acceptable range.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of U.S. Provisional PatentApplication Ser. No. 62/652,581, filed Apr. 4, 2018, the entirety ofwhich is hereby incorporated herein by reference. This application is acontinuation of U.S. patent application Ser. No. 16/006,178, filed Jun.12, 2018, the entirety of which is hereby incorporated herein byreference.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present invention relates to avionics systems and, morespecifically, to a system for warning when cockpit pressurization fallsbelow a threshold.

2. Description of the Related Art

Aircraft cabin pressurization is typically controlled in advancedaircraft, such as fighter jets and commercial jets, using a constantdifferential mode, in which cabin pressure is maintained at a constantpressure difference between the air pressure inside the cabin and theambient air pressure, regardless of aircraft altitude changes. Theconstant differential mode pressure differential is lower than themaximum differential pressure for which the airframe is designed,keeping the integrity of the pressure vessel intact.

In such advanced aircraft, pressurization becomes increasingly necessaryat altitudes above 10,000 feet above sea level to protect the pilot fromthe risk of physiological problems caused by the low outside airpressure above that altitude. Such problems include hypoxia, altitudesickness, decompression sickness, and barotrauma. Hypoxia, results fromreduced partial pressure of oxygen at high altitudes. Hypoxia reducesthe alveolar oxygen tension in the lungs and subsequently in the brain,leading to diminished cognitive factors such as sluggish thinking,dimmed vision and loss of consciousness, which can result in fatalaccidents if experienced by a pilot.

Some existing aircraft include instruments that indicate cabin altitudefor monitoring pressurization. Cabin altitude is the hypotheticalaltitude corresponding to the pressure inside the cabin. For example, apressurized aircraft flying at 40,000 feet above sea level (ASL) couldbe pressurized to a pressure corresponding to 8,000 feet ASL, which isthe aircraft's cabin altitude. The pilot monitors the aircraft altitudeand ensures that the cabin altitude maintains a correct differentialaccording to a pressurization schedule for the aircraft.

However, advanced aircraft pilots are frequently stimulated by importantevents and such stimulation can result in the pilot being distractedfrom issues of pressurization. Also, pilots suffering from hypoxia canfind it difficult to understand numerical digits displayed by monitoringinstruments. As a result, they might have difficulty understandingexisting pressurization monitoring instruments when the aircraft isexperiencing pressure loss.

Therefore, there is a need for a pressurization warning system thatpresents pressurization indications in a format that is quicklycomprehendible by individuals experiencing reduced cognitive ability asa result of hypoxia.

SUMMARY OF THE INVENTION

The disadvantages of the prior art are overcome by the present inventionwhich, in one aspect, is a cockpit pressurization and oxygen warningsystem in an aircraft flown by a pilot and having an aircraft altitudeand a cabin altitude. The system includes a cabin pressure input and anaircraft pressure input. A pilot interface includes a first visualindicator having a first recognizable characteristic disposed in a firstposition that is made visually perceptible when a first signal isasserted and a second visual indicator having a second recognizablecharacteristic esthetically different from the first recognizablecharacteristic and disposed in a second position different from thefirst position that is made visually perceptible when a second signal isasserted. A control circuit that is responsive to the cabin pressureinput and the aircraft pressure input determines an acceptable range forthe cabin altitude that corresponds to the aircraft altitude. Thecontrol circuit asserts the first signal when the cabin altitude iswithin the acceptable range and asserts the second signal when the cabinaltitude is not within the acceptable range.

In another aspect, the invention is a cockpit pressurization monitoringapparatus that includes a cabin pressure input and an aircraft altitudeinput. A control circuit determines cabin altitude as a function of thecabin pressure input and determines an acceptable cabin altitude rangeas a function of the aircraft altitude. A pilot interface, responsive tothe control circuit, includes a first light that illuminates with afirst color when the cabin altitude is within the acceptable cabinaltitude range and includes a second light, spaced apart from the firstlight, that illuminates with a second color, different from the firstcolor, when the cabin altitude is outside of the acceptable cabinaltitude range.

In yet another aspect, the invention is a method of presentingpressurization information to a pilot about an aircraft having anaircraft altitude and a cabin altitude, in which the aircraft altitudeand the cabin altitude are sensed. It is determined if the cabinaltitude is within an acceptable range given the aircraft altitude. Whenthe cabin altitude is within an acceptable range, then a firstindication is generated. When the cabin altitude is not within anacceptable range, then a second indication that is distinguishable fromthe first indication by the pilot when the pilot exhibits diminishedcognitive factors associated with hypoxia is generated.

These and other aspects of the invention will become apparent from thefollowing description of the preferred embodiments taken in conjunctionwith the following drawings. As would be obvious to one skilled in theart, many variations and modifications of the invention may be effectedwithout departing from the spirit and scope of the novel concepts of thedisclosure.

BRIEF DESCRIPTION OF THE FIGURES OF THE DRAWINGS

FIG. 1 is an exploded view of one embodiment of a cockpit pressurizationand oxygen warning system.

FIG. 2 is a cross sectional view of the system shown in FIG. 1.

FIG. 3A-3F are schematic diagrams of a pilot interface employed in thesystem shown in FIG. 1 showing the interface during different cabinaltitude states.

FIGS. 4A-4AQ are depictions of different display configurationsemployable with the present system.

FIGS. 5A-5B are depictions of two different screen formats employablewith the present system.

FIG. 6A is a schematic diagram showing a cockpit pressurization andoxygen warning system coupled to a static pressure line.

FIG. 6B is a schematic diagram showing a cockpit pressurization andoxygen warning system coupled to an electronic static pressure sensor.

DETAILED DESCRIPTION OF THE INVENTION

A preferred embodiment of the invention is now described in detail.Referring to the drawings, like numbers indicate like parts throughoutthe views. Unless otherwise specifically indicated in the disclosurethat follows, the drawings are not necessarily drawn to scale. As usedin the description herein and throughout the claims, the following termstake the meanings explicitly associated herein, unless the contextclearly dictates otherwise: the meaning of “a,” “an,” and “the” includesplural reference, the meaning of “in” includes “in” and “on.”

The present invention collects and presents information regarding thepressurization state of an aircraft's cockpit while in flight.Specifically, the invention detects cabin pressure and compares it tothe aircraft pressure to determine the cabin altitude. If the cabinaltitude is outside of a predetermined range, the invention presents anindication of such a situation in a way that is quickly perceptible bythe pilot. The indication is also presented in a way that is more likelyto be perceived by a pilot experiencing hypoxia-related sensory andcognitive factors. The quick and easily perceived indication of anabnormally low cabin altitude presented by the invention can be animportant factor to a successful recovery from aircraftdepressurization.

As shown in FIG. 1, one embodiment of a cockpit pressurization andoxygen warning system 100 for providing pressurization information to apilot includes a back bezel 140 in which is disposed an electronicsdisplay suite 142 and which is capped by a front bezel 110. Theelectronics and display suite 142 includes an input button board 120that includes buttons used to receive pilot input, rubber key buttoncovers 122 that protects the buttons, a display element 132 such as anorganic light emitting diode (OLED) display for presenting visuallyperceptible information to the pilot, a filter glass 130 that protectsthe display element, a display bracket 133 for holding the displayelement 132 and providing electrical connections thereto, a frontprinted circuit board 134 that is electrically coupled to all displayand input elements and upon which is mounted processor circuitry, and aback printed circuit board 136 that is electronically coupled to thefront printed circuit board 134. An integrated pressure transducer 146(such as the Honeywell IPT0020A33R sensor) is electrically coupled tothe back printed circuit board 136 and senses cabin pressure. A rear can142 protects the integrated pressure transducer 146 and any connectionsto the back printed circuit board 136. An indicator area overlay 112 canbe placed in front of a portion of the display element 132 to presentcertain preselected messages by illuminating the portion of the displayelement 132 upon the occurrence of certain events.

As shown in FIG. 2, one embodiment employs a control circuit to manageand display the relevant data. The control circuit also generates afirst signal when the cabin altitude is within the acceptable range andgenerates a second signal when the cabin altitude is not within theacceptable range. There first signal and the second signal used tocontrol the outputs to the pilot. The control circuit can include amicroprocessor 320 and a digital memory 322 coupled thereto. (As will bereadily appreciated by those of skill in the art, other types of controlcircuits, such as micro-controllers, programmable logic arrays, analogcontrol circuits and proprietary control circuits, etc. may be employedwithout departing from the scope of the invention.) The control circuitreceives cabin pressure input from pressure transducer 146 and staticpressure input from pressure transducer 312, and determines anacceptable range for the cabin altitude that corresponds to the aircraftaltitude, which could be done by accessing a lookup table from thememory 322. A data card input 244 can be used in uploading anddownloading data from a data card 10. The data can include softwareupdates, data log information, diagnostic data, pilot presetpreferences, etc. Such data card input 244 could include interfaces todevices such as: a flash memory card interface (e.g., an SD, XD or CFcard interface), a USB port or one of the many other types of datainterfaces known to the art.

Different states of the pilot interface 200 are shown in FIGS. 3A-3F.The pilot interface 200 includes: a display area 230 that presentsvarious information about the pressurization state of the aircraft, atest button 240 that allows the pilot to run a self-test on the system,a page (or mode) button 242 that allows the pilot to change displaymodes manually, an indicator area 112 that presents certain fixedindicators, a situation-normal LED indicator 220 that indicates whencabin altitude is within a desirable range.

When the pilot depresses the page button 242 a mode signal is assertedand sensed by the control circuit, which causes the electronic displayto cycle to a display mode selected from a plurality of display modes.In one of the display modes, an interface 200 that would be typical fora normally pressurized cabin is shown in FIG. 3A, in which the displayarea 230 shows a numerical cabin altimeter that presents arepresentation of cabin altitude 232 with a hatched rectangle 238covering any leading blank spaces—which aids in the quick recognition ofthe digits by the pilot when low values are being displayed. The displayarea 230 also shows a mode indicator 234, which tells the pilot theselected display mode (which in the example shown is numerical altimetermode). A simple status indicator 236 a (which in this case is “OK”)indicates that cabin altitude is acceptable. The situation-normal LEDindicator 220 is illuminated with a cool color (such as green or blue),which also quickly informs the pilot that the cabin altitude isacceptable. Use of green or another cool color is typically associatedby pilots with acceptable conditions and, therefore, a pilot will bequickly conditioned to recognize normal cabin altitude when this LED isilluminated.

As shown in FIG. 3B, if the cabin altitude is below an acceptable range,a warning indicator 210 is illuminated with a warm color (such as red ororange) and LED 220 is turned off. The warning indicator 210 can be of adifferent shape (e.g., triangular) from that of the situation-normal LEDindicator 220 (e.g., round) to further facilitate easy recognition ofthe different situations. Additionally, the status indicator 236 b(which in this case is “LO”) can provide a confirming indication thatcabin altitude is below the desired range. The cabin altimeter 232 inthis case shows a low number, which is made easier to recognize by thehatched rectangle 238 covering the leading blank area. A changeindicator 235, which in this case is a downwardly-pointing triangle,indicates that the cabin altitude is decreasing. This situation couldalso be coupled with an audible alarm, which could further facilitateeasy recognition by a pilot who might be experiencing hypoxia-relatedcognitive impairment.

As shown in FIG. 3C, the status indicator 236 b could indicate that thecabin altitude 232 is fluctuating, which can be a normal condition ifthe aircraft is performing certain maneuvers.

As shown in FIG. 3D, the cabin altitude 232 can be high, which is thesituation that might indicate depressurization and can result in pilothypoxia. In this case, status indicator 236 d indicates that the cabinaltitude is “HI” and the warning indicator 210 is illuminated. Because,warning indicator 210 is spaced apart from LED 220 and because warmcolors (such as red) generally connote alarm conditions, the pilot islikely to recognize a potentially dangerous situation quickly, eventhough the pilot might already be experiencing some of the cognitiveeffects associated with hypoxia.

As shown in FIG. 3E, one of the display modes shows rolling digits 239in the manner of an analog altimeter. As shown in FIG. 3F, one of thedisplay modes shows a bar graph 250 of cabin altitude over time.

As shown in FIGS. 4A-4AQ, the display can have many different modes thatcan be selectable by the pilot and by technicians working on the system.While the displays are shown as white characters on a black background,in night mode they would typically be represented as green characters ona black background and in daylight mode they could be represented asblack characters on a white background. The mode selection could be mademanually by the pilot or automatically based on time/location or sensedambient light. Also, in some embodiments, other colors could beselectable by the pilot or technician. The display can also have eithera two row format, as shown in FIG. 5A, or a one row format, as shown inFIG. 5B.

As shown in FIG. 6A, the cockpit pressurization and oxygen warningsystem 100 can be configured to work with an aircraft having a standardstatic port 22 opening through the aircraft's skin 20 and coupled to astatic pressure air line 24, to which is coupled such instruments as anairspeed indicator 12, a vertical speed indicator 14 and an altimeter16. The warning system 100 receives a static pressure indication fromthe static pressure line 24 and a pressure transducer 312 converts thestatic pressure to an electronic signal representative thereof. Anelectronic pressure transducer 146 measures cabin pressure and generatesan electronic signal representative thereof. If the aircraft employs adigital static pressure sensor 30, as shown in FIG. 6B, the warningsystem 100 receives a static pressure indication from a static pressuresignal wire 34.

In one representative embodiment, the cockpit pressurization and oxygenwarning system 100 can include the following components:

Cockpit Pressure Altimeter (CPA)

Displays and records data including altitude

OBOGS Concentrator Outlet Pressure Sensor (COPS)

Measures pressure of the OBOGS concentrator

Nose Wheel Well pressure sensor (NWW)

Provides altitude reference for CPA

In one representative embodiment, the cockpit pressurization and oxygenwarning system 100 can be configured into the following modes:

CPOMS 1—uses NWW sensor for altitude reference

CPA-101

COPS-103

NWW-105

CPOMS 2—uses FCC/ADC for altitude reference

CPA-101

COPS-103

The above described embodiments, while including the preferredembodiment and the best mode of the invention known to the inventor atthe time of filing, are given as illustrative examples only. It will bereadily appreciated that many deviations may be made from the specificembodiments disclosed in this specification without departing from thespirit and scope of the invention. Accordingly, the scope of theinvention is to be determined by the claims below rather than beinglimited to the specifically described embodiments above.

What is claimed is:
 1. A cockpit pressurization and oxygen warningsystem in an aircraft flown by a pilot and having an aircraft altitudeand a cabin altitude, comprising: (a) a cabin pressure input; (b) anaircraft pressure input; (c) a pilot interface including a first visualindicator having a first recognizable characteristic disposed in a firstposition that is made visually perceptible when a first signal isasserted and a second visual indicator having a second recognizablecharacteristic aesthetically different from the first recognizablecharacteristic and disposed in a second position different from thefirst position that is made visually perceptible when a second signal isasserted; and (d) a control circuit that is responsive to the cabinpressure input and the aircraft pressure input that determines anacceptable range for the cabin altitude that corresponds to the aircraftaltitude and that determines the cabin altitude as a function of thecabin pressure input and that asserts the first signal only when thecabin altitude is within the acceptable range and not when the cabinaltitude is not within the acceptable range, and that asserts the secondsignal only when the cabin altitude is not within the acceptable rangeand not when the cabin altitude is within the acceptable range.
 2. Thecockpit pressurization and oxygen warning system of claim 1, wherein thefirst visual indicator comprises a first light emitting device thatemits light of a first color and wherein the second visual indicatorcomprises a second light emitting device that emits light of a secondcolor that is different from the first color.
 3. The cockpitpressurization and oxygen warning system of claim 1, wherein the firstvisual indicator comprises a first light emitting device that emitslight in a first shape and wherein the second visual indicator comprisesa second light emitting device that emits light in a second shapedifferent from the first shape.
 4. The cockpit pressurization and oxygenwarning system of claim 3, wherein the first shape includes a circularshape and wherein the second shape includes a triangular shape.
 5. Thecockpit pressurization and oxygen warning system of claim 1, wherein thepilot interface further comprises an electronic display and a manualmode input and wherein the electronic display is configured to display anumerical cabin altimeter.
 6. The cockpit pressurization and oxygenwarning system of claim 5, wherein the electronic display is configuredto display a hatched region in a region in which numerical informationis not displayed and that is disposed immediately adjacent to and leftof a region in which numerical information is displayed, therebyfacilitating recognition of low values by the pilot.
 7. The cockpitpressurization and oxygen warning system of claim 5, wherein mode inputcomprises a button that, when depressed, asserts a mode signal sensed bythe control circuit, wherein when the mode signal is asserted thecontrol circuit causes the electronic display to cycle to a display modeselected from a plurality of display modes including: a numerical cabinaltimeter; a numerical cabin altimeter with rolling numbers; and a bargraph representation of cabin altitude over time.
 8. The cockpitpressurization and oxygen warning system of claim 5, wherein the controlcircuit generates an indicator shown on the electronic display thatindicates a cabin altitude state selected from a list of statesconsisting of: acceptable signified by the letters “OK”, fluctuatingsignified by the letters “FLUC,” above desired range signified by theletters “HI” and below desired range signified by the letters “LO.” 9.The cockpit pressurization and oxygen warning system of claim 8, whereinthe control circuit displays the letters “OK” with a first backgroundand displays the letters “FLUC,” “HI” and “LO” with a second backgrounddifferent from the first background.
 10. An avionics interface devicefor presenting information to a pilot, comprising: (a) an avionics datainput; and (b) a display device that presents a numerical representationof data from the avionics data input and that presents a hatchedrectangle immediately adjacent to and left of the numericalrepresentation of data in substitution for any leading blank spaces thatwould otherwise be presented to the left of the numerical representationof data, thereby aiding in quick recognition of the numericalrepresentation of data by the pilot when low values are being displayed.11. The avionics interface device of claim 10, embodied in a cockpitpressurization monitoring apparatus and oxygen warning system in anaircraft flown by a pilot and having an aircraft altitude and a cabinaltitude, wherein the avionics data input comprises a cabin pressureinput and an aircraft pressure input and wherein the display deviceincludes a pilot interface including a first visual indicator having afirst recognizable characteristic disposed in a first position that ismade visually perceptible when a first signal is asserted and a secondvisual indicator having a second recognizable characteristicaesthetically different from the first recognizable characteristic anddisposed in a second position different from the first position that ismade visually perceptible when a second signal is asserted, and furthercomprising a control circuit that is responsive to the cabin pressureinput and the aircraft pressure input that determines an acceptablerange for the cabin altitude that corresponds to the aircraft altitudeand that determines the cabin altitude as a function of the cabinpressure input and that asserts the first signal only when the cabinaltitude is within the acceptable range and not when the cabin altitudeis not within the acceptable range, and that asserts the second signalonly when the cabin altitude is not within the acceptable range and notwhen the cabin altitude is within the acceptable range.
 12. The avionicsinterface device of claim 11, wherein the first visual indicatorcomprises a first light emitting device that emits light of a firstcolor and wherein the second visual indicator comprises a second lightemitting device that emits light of a second color that is differentfrom the first color.
 13. The avionics interface device of claim 11,wherein the first visual indicator comprises a first light emittingdevice that emits light in a first shape and wherein the second visualindicator comprises a second light emitting device that emits light in asecond shape different from the first shape.
 14. The avionics interfacedevice of claim 13, wherein the first shape includes a circular shapeand wherein the second shape includes a triangular shape.
 15. A methodof presenting pressurization information to a pilot about an aircrafthaving an aircraft altitude and a cabin altitude, comprising the stepsof: (a) sensing the aircraft altitude and the cabin altitude; (b)determining if the cabin altitude is within an acceptable range giventhe aircraft altitude; (c) only when the cabin altitude is within anacceptable range and not when the cabin altitude is not within theacceptable range, then generating a first indication; and (d) only whenthe cabin altitude is not within an acceptable range and not when thecabin altitude is within the acceptable range, then generating a secondindication that is spaced apart from the first indication and that isvisually distinguishable from the first indication, wherein the step ofgenerating a first indication comprises the step of illuminating a firstvisual indicator having a first color and a first shape and wherein thestep of generating a second indication comprises the step ofilluminating a second visual indicator spaced apart from the firstvisual indicator and having a second color different from the firstcolor and a second shape different from the first shape.
 16. The methodof claim 15, further comprising the step of displaying a first textualindicator indicating acceptable cabin altitude and wherein the step ofgenerating a second indication comprises the step of displaying a secondtextual indicator indicating unacceptable cabin altitude.
 17. The methodof claim 15, further comprising the step of displaying a representationof the cabin altitude in a numerical cabin altimeter.
 18. The method ofclaim 17, wherein the step of displaying a representation of the cabinaltitude further comprises the step of displaying a numerical cabinaltimeter having rolling numbers.
 19. The method of claim 17, whereinthe step of displaying a representation of the cabin altitude furthercomprises the step of displaying a bar graph representing cabin altitudeover time.
 20. The method of claim 17, further comprising the step ofdisplaying a hatched region in a region in which numerical informationis not displayed and that is disposed adjacent to and left of a regionin which numerical information is displayed, thereby facilitatingrecognition of low values by the pilot.